In recent years, treating the wastewater from potato processing facilities has become a serious environmental concern, as well as a large expense. These facilities process “raw” harvested potatoes into consumer products such as french fries, criss-cut fries, wedges, hash browns, granules, flakes, slices, and other various frozen and dehydrated products. Water is integral to the process and often contains solid potato pieces that are considered to be waste products. Therefore, it is desirable to have a process that would utilize such waste products in the final product and minimize the amount of waste at the end of the process that needs to be treated.
U.S. Pat. No. 5,997,652 to Potter et al. describes a food starch processing method and apparatus. The apparatus, a food starch separator, comprises a serially connected centrifuge and a membrane separator further comprising a sintered pipe providing pore flow paths including a pumped source of food plant liquor, outputs for the centrifuge and membrane separator and a control system to regulate the flow of the food plant liquor. In a modified batch operation with feedback, flow is directed through a first centrifuge, a second centrifuge and then through a membrane separator. The flow is then delivered out of the membrane separator and directed to a feedback line that returns the concentrate from the membrane separator to a tank that is refilled with the feedback flow. As this process occurs, some portion of the solvent is recovered and some portion of the starch and pulp material is segregated and removed. The batch can be terminated by obtaining specified concentrate strength. Potter et al. fail to disclose a manufacturing process that produces a product containing a portion of the solids from the process water and wherein the final characteristics of the product remain essentially unchanged.
U.S. Pat. No. 6,736,903 to Minazzoli describes a method and apparatus for producing a work product. In practicing this method, a first fluid composed of a liquid, a target substance and at least one residual substance is received. The first fluid is passed through a means for separating the residual substance from the first fluid to produce a secondary fluid substantially composed of the liquid and the target substance. The secondary fluid is treated to reduce the proportion of the liquid relative to the target substance in the secondary fluid to form the work product. Minazzoli discloses that the resultant product may be converted for reuse; have a useful purpose in its own right; be of independent commercial use and value; or useful for a wide variety of purposes and different applications. However, Minazzoli fails to disclose that the product produced from the manufacturing process contains a portion of the solids from the process water and that the final characteristics of the product remain essentially unchanged.
U.S. Pat. No. 5,593,598 to McGinness et al. discloses a method and apparatus for closed loop recycling of contaminated cleaning solution. In particular, they describe a method wherein the rinse water from the cleaning process is separated by reverse osmosis into a reconcentrated reusable cleaning solution and clean reusable recyclable rinse water. The reconcentrated reusable cleaning solution is then returned back to the original cleaning process and the cleaning solution station, and the reverse osmosis product water is returned to the original rinse station for reuse. However, this process focuses on the separation of a liquid cleaning solution from the rinse water. Moreover, in this closed loop process, the cleaning solution is continuously reconcentrated from the rinse water and the cleaning solution is returned back to the original cleaning process for reuse and the rinse water is returned to the rinse station. The present invention is an open loop process where a final product is derived from the process such that it contains a portion of the solids from the original process water and wherein the final characteristics of the product remain essentially unchanged.
Liaw et al. in U.S. Pat. No. 6,658,978 describe a membrane filtration process for thickening and starch washing in corn wet milling. The process comprises the steps of (1) separating wet milled de-germed corn particles into a fiber component and a first stream comprising water, starch, and protein (e.g. fiber separation step); (2) performing membrane filtration of the first stream (e.g. starch-protein stream thickening) producing a first retentate and a first aqueous permeate; (3) and separating the first retentate (e.g. thickened starch-protein stream) into a second stream and a third stream (e.g. primary starch separation step), wherein the second stream comprises water and a majority of the starch present in the first retentate, and the third stream comprises water and a majority of the protein present in the first retentate. The second stream comprises more than half of the starch that was present in the first retentate (thickened starch-protein stream). Liaw et al. fail to disclose a step in the process where the second stream is reintroduced into at least one vessel in the manufacturing process such that the resulting product from the process contains a portion of the solids from the process water and the final characteristics of the product remain essentially unchanged.
U.S. Pat. No. 5,374,356 to Miller et al. describes a fluid treatment process using dynamic microfiltration and ultrafiltration. In this process, wastewater is treated by passing wastewater into a dynamic microfiltration assembly to form a first concentrate stream and a filtrate stream and then passing the filtrate stream into an ultrafiltration assembly to form a second concentrate stream and a purified water stream. The purified water stream can then be further treated, recycled, and/or discharged as appropriate. The first and second concentrate stream can be further processed or held for proper disposal. Miller et al. fail to disclose the reincorporation of the second concentrate stream into the process to produce a product containing a portion of the solids from the process water. In fact, based on the teaching of Miller et al., it would be undesirable to do so because their process is directed toward wastewater treatment.
U.S. Pat. No. 4,412,867 to Cicuttini describes a wet milling process for starch bearing materials (e.g. corn, potatoes or wheat) wherein water being used in the process is separated by reverse osmosis or ultrafiltration. One fraction (the first fraction) has a lower content of soluble and insoluble matter than the other (second) fraction. The first fraction is then recycled to the washing step in the milling process where it is used to wash the starch. The separation and recycling steps reduce the water requirement of the milling process and also reduce the volume of effluent leaving the process, which needs to be evaporated and/or disposed of. As in Miller et al., Cicuttini fails to disclose a method whereby the second fraction is incorporated into the final product, producing a product containing a portion of the solids from the process water.
An object of the present invention is to provide a method for filtering and recovering solids from potato process water and reintroducing those solids back into the process such that the resulting product contains a portion of the solids from the potato process water.